Ruthenium Acetylide Oxidation: From Stable Radicals to Allenylidene Synthesis via -Elimination of H+
Résumé
Oxidation of ruthenium(II) acetylides trans-[Cl(dppe)2Ru-CC-CHR2] (R = H, CH3, Ph) leads to cationic radicals of which the stability is found to be highly influenced by the nature of R. This oxidative process leads to a stable cationic radical (R = CH3, H) or to its rearrangement into a neutral radical, trans-[Cl(dppe)2Ru-CC-C(R)2] for R = Ph. This unprecedented -elimination of a proton provides both the allenylidene trans-[Cl(dppe)2Ru=C=C=CR2]PF6 and the vinylidene trans-[Cl(dppe)2Ru=C=CH-CHR2]PF6. The allenylidene can be selectively obtained from the acetylide in the presence of a base